The transmission of the luminance component and the chrominance component of a color television signal with full band-width is often impractical or unnecessary. For example, the television signal may be recorded on and played back from a mechanically playable disc which can provide a band-width which is suitable for a luminance signal but is not suitable for the simultaneous transmission of all the chrominance information as well. It has been proposed to transmit only one chrominance component at a time in line sequence and to reconstitute the television signal at a receiver by delaying the received signal by a sufficient number of lines to make all the chrominance components in one cycle of the sequence simultaneously available. Such a technique is exemplified by the arrangements described in, for example, British Patent Specification No. 1185197 and U.S. Pat. No. 3,560,635. When three chrominance components are transmitted in this manner the chromatic content of any line in a reconstituted television picture is formed in part from the content of two preceding lines and accordingly there is necessarily a loss in the definition of the picture in the "vertical" sense. Because the human eye is relatively insensitive to high frequency colour variations, one may, as the aforementioned specifications disclose, improve the definition of a television picture of which the chrominance content is of low frequency by the addition of high-frequency luminance signals. This technique envisages the transmission of a luminance signal combined with a chrominance component which is of lesser band-width than the luminance signal and usually occupies the lower frequency end of the band-width allowed for transmission of the luminance signal. Such a combined signal can be transmitted through a channel of the same band-width as is required for a signal containing only luminance information. However, in recovering from such a combined signal the chrominance components using, for example, two delay-lines to render these components simultaneously available, at least part of the signal is averaged over a number of lines to form each line of the output luminance signal and accordingly there is a considerable loss of the vertical detail in the luminance signal, since this detail is at least partly contained in the lower frequency end of the luminance signal.